Search continues for Donald Mackay

Police say the search for the remains of anti-mafia campaigner Donald Mackay will be a lengthy process.

Crews from New South Wales, Australian Federal Police have been searching a small area of two adjoining properties near Hay in the state's Riverina since Tuesday.

They're acting on a tip-off that Mr Mackay's body may have been dumped there shortly after his murder in Griffith in 1977.

Superintendent Michael Rowan told Hay residents this morning nothing of interest has been found yet, but it's a long road ahead.

"At this stage it's a search for remains," said Mr Rowan.

"The process we're going to be going through, it will be detailed, it will be painstaking and it will take a significant period of time."

The states Homicide Commander, Michael Willing says an extensive search is underway which will take time.

"There are nine persons from the forensic services area who are assisting detectives with enquiries," said Commander Willing.

"Along with detectives from the unsolved homicide team in Griffith at the moment working with local detectives."

"The area itself we are focusing on is around 50 metres by 30 metres, however if required, we will extend that."

Police remain tight lipped about the tip off that led to them to excavate the area.

Detective Superintendent of Griffith Local Area Command Michael Rowan says in December 2011 police received an anonymous source pointing to the site, but there are also others in question.

Superintendent Rowan believes members of the community are still concealing the truth.

"No look I can't say where the information came from, the information when it originally came from us was anonymous information so I'm really not able to say where it actually came from," said the Superintendent.

"I am still of the view that there are people in the community that know what took place and and I would encourage those people to contact us."

Commander Willing also says the police won't budge on revealing anything about the tip-off.

"I am not at liberty to say exactly what we are looking for however we are focussing on a particular area."